Damage. That part is incuse on the die itself. There’s no way it broke off, as that would leave a raised area. The other explanation would be grease filled, but that wouldn’t have such a sharp line from the part where the letter is there and where it is missing. Which leaves only damage. Sorry.
DEFDAM - Definitely Damage The E took a hit. Years of circulation wear eliminated the evidence. Copper is soft enough to be moved and smoothed.
